Method and medical device for reducing the effects of interference generated by a radio transmission from the medical device

ABSTRACT

A method of processing in a medical device an electric biological signal collected from a patient, includes: a) acquiring a plurality of samples from the electric biological signal according to a sampling process wherein each sample is taken from the electric biological signal and memorized; b) during the sampling process of a), monitoring an active/inactive status of a radio time-division-multiplexing transmission of signals from the medical device over a radio communication network; and, when the status of the radio time-division-multiplexing transmission becomes active, c) preventing in a) the acquisition of any of the plurality of samples, which according to the sampling process should be acquired during the active status of the radio time-division-multiplexing transmission, from being performed until the radio time-division-multiplexing transmission remains in the active status.

The present invention relates to the field of medical telemetry.

In particular, it relates to the field of medical telemetry wherein amedical device remotely collects an electric biological signal from apatient, processes the collected electric biological signal andtransmits processed data to a centralized monitoring station over aradio communication network. From the centralized monitoring station, atechnician or a doctor can monitor in real time the physiologic statusof the patient.

For example, the electric biological signal may be an electric cardiacsignal or an electric signal associated with activity of skeletalmuscle.

The centralized monitoring station and/or the remote telemeter maysupport suitable diagnostic function for alerting the technician/doctorand/or the patient whenever a predetermined physiologic event occurs,such as a cardiac arrhythmia condition.

US 2001/0023315 discloses a medical telemetry system for collectingreal-time physiological data of patients of a medical facility, and oftransferring the data via RF (Radio Frequency) to a real-time datadistribution network for monitoring and display. The system includesbattery-powered remote telemeters which attach to respective patients,and which collect and transmit (in data packet) the physiological dataof the patients.

The remote telemeters communicate bi-directionally with a number ofceiling-mounted RF transceivers using a wireless TDMA (Time DivisionMultiple Access) protocol. The RF transceivers, which are hard-wireconnected to a LAN, forward the data packets received from thetelemeters to patient monitoring stations on the LAN.

JP 2002 219109 discloses a system wherein patient's ECG information istransmitted to an automatic diagnostic analyzer at a supervisory centreby cellular phone.

Paul A. Roche et al. (“Using a Cell Phone for Biotelemetry”, proceedingsof the 2005 IEEE 31^(st) Annual Northeast Bioengineering Conference, p.65-66) discuss the benefits, obstacles, and methods of using cell phonesto transmit biological waveforms to increase the mobility of patientmonitoring. The Authors state that shielding the input cables willreduce the differential RF interference. Moreover, they state that theimmunity of the sensitive electronics can be increased by insertinglow-pass filters with maximum insertion loss at the cell phone'stransmission frequency, reducing the RF seen at the inputs.

EP 1 589 464 discloses a diagnostic device comprising different sensorswhich can collect different electric biological signals such as heartrate, arterial pressure etc.; an analog-to-digital converter; a portablesignal receiver which can analyze and process digitally converted data;and a transmission module to activate tele-transmission, via a telephonemodem or GSM, to a central server. This document states that theanalog-to-digital converter is placed close to the sensors so that thesignals can be converted immediately on reception and transmitteddigitally which is easier to manage and significantly reduces externalinterference.

As to the techniques disclosed by the above mentioned Paul A. Roche etal. to reduce interference problems, the Applicant notes that cableshielding can be insufficient. In particular, cable shielding can beinadequate to reduce interference occurring at the cable junctions(e.g., in the proximity of electrodes and connectors).

Moreover, as to the low-pass filtering technique disclosed by Paul A.Roche et al., the Applicant notes that such technique can be notadequate when an analog to digital (A/D) conversion of the collectedbiological waveform has to be performed for further data processing. Infact, in these cases, according to Shannon theorem, the collectedbiological waveform will be typically sampled at a sampling frequencythat is at least twice the biological frequency range (which is usuallybelow 200 Hz). Moreover, in order to improve performances, thebiological waveform will be typically over-sampled at a samplingfrequency that is at least three or four times the biological frequencyrange. Therefore, considering that medical devices with high accuracyand sensitivity may use a sampling frequency of 500 Hz, the cut-offfrequency of the low-pass filter should be of at least 250 Hz.Therefore, a low-pass filter with cut-off frequency of not less of 250Hz will be not adequate to filter out the GSM (Global System for Mobilecommunications) standard's demodulated frame rate of 217 Hz.

The Applicant started from the observation that, between the collectedelectric biological signals and the signals transmitted by the medicaldevice through a radio communication network, interferences may occur atthe cable conveying the collected electric biological signals from theelectrodes in contact with the patient's body to the medical device andat the junction points of the cable. He has remarked that suchinterference may significantly disturb the electric biological signalacquisition to the extent that the electric biological signal may resultundecipherable and a diagnostic algorithm inapplicable.

Accordingly, the Applicant faced the technical problem of effectivelyreducing the effects of interference in a medical device.

In particular, the Applicant faced the technical problem of providing amethod of electric biological signal processing and a medical devicethat allow to significantly reduce the effects of the interferencebetween a collected electric biological signal and a signal transmittedby the medical device through a radio communication network that uses atime-division-multiplexing transmission scheme.

The Applicant found that this problem can be solved by sampling theelectric biological signal collected from the patient; keepingmonitoring the status (active/inactive) of the radiotime-division-multiplexing transmission used by the medical device tosend signals over a radio communication network; and, during thesampling process, preventing acquisition of any electric biologicalsignal sample, which according to the sampling process should beperformed during an active status of the radiotime-division-multiplexing transmission, from being performed till theradio time-division-multiplexing transmission remains active.

Accordingly, in a first aspect the present invention relates to a methodof processing in a medical device an electric biological signalcollected from a patient, the method comprising:

a) acquiring a plurality of samples from the electric biological signalaccording to a sampling process wherein each sample is taken from theelectric biological signal and memorized;

b) during the sampling process of a), monitoring an active/inactivestatus of a radio time-division-multiplexing transmission of signalsfrom the medical device over a radio communication network; and, whenthe status of said radio time-division-multiplexing transmission becomesactive,

c) preventing in a) the acquisition of any of the plurality of samples,which according to said sampling process should be acquired during saidactive status of the radio time-division-multiplexing-transmission, frombeing performed till the radio time-division-multiplexing transmissionremains in said active status.

In the present description and claims the expression “sampleacquisition” is used to indicate both the action of taking a sample froman analog electric biological signal and the action of memorizing thetaken sample. Acquisition of a sample is prevented if at least one ofthe two actions is not performed. In particular, sample acquisition canbe prevented if the sample is not taken and no value for the not takensample is memorized, or if the sample is not taken but a predeterminedvalue for the not taken sample is memorized, or if the sample is takenbut not memorized as it is.

Advantageously, the sampling process in a) is a periodic samplingprocess having a sampling period T1. Within each interval of time T1,sample acquisition is advantageously performed for a predeterminedactive time slot Ts1, with Ts1<T1. Within each predetermined active timeslot Ts1 at least one sample is advantageously acquired.

Advantageously, according to said radio time-division-multiplexingtransmission, signal transmission is performed according to atransmission period T2. Moreover, within each interval of time T2,signal transmission is advantageously active for a predetermined activetime slot Ts2, with Ts2<T2.

Advantageously, samples are acquired in a) at an acquisition rate 1/T1that is at least twice the frequency range of the collected electricbiological signal. Advantageously, the acquisition rate 1/T1 is higherthan at least twice the frequency range of the collected electricbiological signal.

Advantageously, when the status of said radio time-division-multiplexingtransmission becomes inactive again, the sampling process of a) isresumed.

Advantageously, the monitoring in b) is continuously carried on duringthe execution of a).

Advantageously, when in b) the status of said radiotime-division-multiplexing transmission is inactive the sampling processof a) is carried on.

According to a first embodiment, c) is performed by preventing any ofthe plurality of samples, which according to said sampling processshould be acquired during the active status of the radiotime-division-multiplexing transmission, from being taken and memorizedtill the radio time-division-multiplexing transmission remains in saidactive status.

In the first embodiment, b) is advantageously performed in parallel toa).

Typically, the electric biological signal is collected through n analoginput channels, wherein n is an integer at least equal to 2. As known inthe art, in case of ECG electric biological signal, n is typically equalto three or ten. Advantageously, within each active acquisition timeslot Ts1, n samples are acquired (a sample of each of the n analog inputchannels is acquired).

In the case in which, in the first embodiment, n samples are acquiredwithin each active acquisition time slot Ts1 and when in b) the statusof said radio time-division-multiplexing transmission becomes active,the method advantageously further comprises d) checking if sampleacquisition in a) is momentarily active (that is, if the samplingprocess in a) is within one of the predetermined active time slots Ts1).

Advantageously, c) is executed in the negative case of d). Preferably,c) is executed only in the negative case of d).

In the positive case of d), the execution of a) (and b)) is carried on.

Moreover, if—during the interval of time said radiotime-division-multiplexing transmission has been active—sampleacquisition has been prevented in c), the sampling process of a) isadvantageously resumed with a predetermined delay Tx lower than T1.Advantageously, the following condition is met: 0<Tx≦Ts1.

Moreover, in the first embodiment, within each active acquisition timeslot Ts1 of the sampling process of a), after taking each of the nsamples and before memorizing it, the method further comprises e)checking if said radio time-division-multiplexing transmission is in anactive status. In the positive case of e), the value of the taken sampleis corrected according to a predetermined correction procedure and thevalue of the corrected sample is memorized. In the negative case of e)the value of the taken sample is memorized as it is.

The correction in e) can be performed, for example, by setting the valueof the taken sample to zero or by replacing the value of the takensample with the value of the corresponding second-last acquired sample(that is, with the value of the sample memorized in the previousacquisition time slot Ts1 for the same channel).

According to a variant, in a), within each active acquisition time slotTs1, before taking each of the n samples, the method further comprisese′) checking if said radio time-division-multiplexing transmission is inan active status. In the positive case of e), the sample is not takenand a predetermined value is memorized for the not taken sample. Forexample, the value of the second-last acquired sample or, according to avariant, a null value is memorized for the not taken sample. In thenegative case of e′), the sample is taken and memorized as it is.

According to a second embodiment, b) is performed by monitoring theactive/inactive status of said radio time-division-multiplexingtransmission after taking each of the plurality of samples in a). Whenthe status of said radio time-division-multiplexing transmission becomesactive, c) is performed by not memorizing the taken sample.Advantageously, the value of the taken sample is corrected according toa predetermined correction procedure. Then, the value of the correctedsample is advantageously memorized.

The correction can be performed, for example, by setting the value ofthe taken sample to zero or by replacing the value of the taken samplewith the value of the second-last acquired sample (that is, with thevalue of the sample memorized in the previous acquisition time slot Ts1for the same channel).

According to a third embodiment, b) is performed by monitoring theactive/inactive status of said radio time-division-multiplexingtransmission before taking each of the plurality of samples in a). Whenthe status of said radio time-division-multiplexing transmission becomesactive, c) is advantageously performed by not taking the sample.Advantageously, a predetermined value is memorized for the not acquiredsample. For example, the value of the second-last acquired sample or,according to a variant, a null value is memorized for the not acquiredsample.

Said radio time-division-multiplexing transmission advantageously is atime division multiple access transmission (TDMA).

Said radio time-division-multiplexing transmission is performedaccording to at least one cellular transmission standard selected fromthe group comprising: GSM, GPRS and EGPRS (Enhanced GPRS).

Said radio communication network can be a GSM, GSM/GPRS and/or GSM/EGPRSmobile network.

In a second aspect the present invention relates to a medical devicecomprising input modules for collecting an electric biological signal,processing modules connected to the input modules, and a transceiversection comprising a mobile data terminal connected to the processingmodules, the transceiver section being adapted to be connected to aradio communication network and to transmit and receive signals by usinga time-division-multiplexing transmission and the processing modulesbeing adapted:

a) to acquire a plurality of samples from the collected electricbiological signal according to a sampling process wherein each sample istaken from the collected electric biological signal and memorized;

b) during the sampling process of a), to monitor an active/inactivestatus of the radio time-division-multiplexing transmission of signalsfrom the transceiver section; and, when the status of said radiotime-division-multiplexing transmission becomes active,

c) to prevent in a) the acquisition of any of the plurality of samples,which according to said sampling process should be acquired during saidactive status of the radio time-division-multiplexing transmission, frombeing performed till the radio time-division-multiplexing transmissionremains in said active status.

As far as concerns further features of actions a) to c) reference ismade to what already disclosed above with reference to the first aspectof the invention.

The transceiver section is advantageously adapted to transmit/receivesignals according to GSM, GSM/GPRS and/or GSM/EGPRS cellulartransmission standards.

The signals transmitted by the transceiver section can include textand/or multimedia messages, data concerning the acquired electricbiological signal and GSM/GPRS/EGPRS signaling.

The transceiver section is advantageously adapted to transmit saidsignals through a Short Messaging System (SMS), a Multimedia MessagingSystem (MMS), and/or a suitable file transfer protocol (e.g., FTP).

Said mobile data terminal is advantageously also adapted to receivesignals through SMS and, optionally, MMS.

Said mobile data terminal is also advantageously adapted to supportsignaling communications with the radio communication network to beenabled to access GSM, GSM/GPRS and/or GSM/EGPRS network services.

Advantageously, the mobile data terminal is adapted to provide theprocessing modules with data indicative of the status (active/inactive)of the radio time-division-multiplexing transmission. The processingmodules are advantageously adapted to determine the status of the radiotime-division-multiplexing transmission by reading said data.

Advantageously, the medical device further comprises a user interface.

Advantageously, the input modules are adapted to receive the electricbiological signal from a cable that connects the input modules toelectrodes to be positioned on the patient's body.

Typically, the input modules comprise n input channels (wherein n is aninteger≧2) for receiving the electric biological signal collected by acorresponding number of electrodes.

Advantageously the medical device is a portable device.

According to an embodiment, the medical device is an electrocardiograph.

According to an embodiment, the medical device is an electromyograph.

The features and advantages of the present invention will be madeapparent by the following detailed description of some exemplaryembodiments thereof, provided merely by way of non-limiting examples,description that will be conducted by making reference to the attacheddrawings, wherein:

FIG. 1 schematically shows an embodiment of a medical device accordingto the invention;

FIG. 2 schematically shows a time diagram of an ECG acquisition process;

FIG. 3 schematically shows a time diagram of a TDMA transmission processaccording to GSM standard;

FIG. 4 schematically shows a time diagram of a TDMA transmission processaccording to GPRS and EGPRS standards;

FIGS. 5 and 6 schematically show a flowchart outlining the main actionscarried out to process an electric biological signal according to afirst embodiment of the invention;

FIG. 7 schematically show a flowchart outlining the main actions carriedout to process an electric biological signal according to a variant ofthe embodiment of FIGS. 5 and 6;

FIG. 8 schematically show a flowchart outlining the main actions carriedout to process an electric biological signal according to a secondembodiment of the invention;

FIG. 9 schematically show a flowchart outlining the main actions carriedout to process an electric biological signal according to a thirdembodiment of the invention.

FIG. 1 schematically shows a medical device 1 according to anexemplarily embodiment of the invention.

Advantageously the medical device 1 is a portable device.

The medical device 1 of FIG. 1 comprises a cable 2, input modules 3,processing modules 4, a user interface 5, power supply modules 6 and atransceiver section 7, comprising a mobile data terminal 8 and aradiating element 9.

The cable 2 comprises a number of wires (not shown), each wire beingterminated at one end by an electrode (not shown) to be positioned incontact with a patient's body. Moreover, the cable 2 comprises aconnector (not shown) for connection of the wires to the input modules3, which receives the electric biological signals from a number of inputchannels (not shown).

For example, in case of ECG acquisition, the ECG cable 2 mayconventionally comprise five surface electrodes: three to be positionedat the position of three standard ECG leads, one as reference electrodeand one as ground electrode. The five electrodes can be positioned onthe patient's chest and three wires can connect the three electrodes tobe positioned at the position of three standard ECG leads to three inputchannels of the input modules 3.

The cable 2 is advantageously shielded according to techniques wellknown in the art to reduce external interference.

The input modules 3 are adapted to process, according to techniques wellknow in the art, the analog electric biological signals collected by theelectrodes, including, for example, amplification and filtering.Advantageously, each input channel is associated with a low-pass filter.The cut-off frequency can be the same for all input channels and is forinstance of 250 Hz.

The power supply modules 6 are adapted to manage power supply of medicaldevice 1, according to techniques well known in the art.

Advantageously the medical device 1 is battery supplied.

The transceiver section 7 is adapted to establish radio communicationswith a remote processing unit (not shown), such as an applicationserver, through a radio communication network, by using atime-division-multiplexing transmission scheme.

According to an embodiment of the invention, radio communications areestablished according to GSM or GSM/GPRS and/or GSM/EGPRS standards.

In this case, transceiver section 7 is advantageously adapted to accessGSM, GSM/GPRS and/or GSM/EGPRS radio mobile network services, receiveand send SMS/MMS messages, and send data files through a GPRS or EGPRSconnection (e.g., according to a File Transfer Protocol or FTP).

For connection to the GSM/GPRS/EGPRS network, the mobile data terminal 8is advantageously equipped with a Subscriber Identity Module (SIM)identified by a univocal client number, i.e., the IMSI (InternationalMobile Subscriber Identity), and a dialable number, i.e., the MSISDNaccording to the standards, at which the transmission module can bereached.

The radiating element 9 is connected to the mobile data terminal 8 andadvantageously comprises a conventional antenna to receive/send radiosignals within GSM/GPRS/EGPRS frequency bandwidths.

The cable connecting the radiating element 9 to the mobile data terminal8 is advantageously shielded according to techniques well known in theart to reduce interference.

Signal transmission towards the remote processing unit may be operatedeither by the patient, by a suitable diagnostic algorithm (according topredetermined pathological criteria) or by the remote processing unit.

The user interface 5 will typically comprise a liquid crystal displayand a keyboard so as to allow the patient to configure the medicaldevice; to display medical data (e.g., ECG patterns); to displayinformation about an anomalous event (e.g., cardiac arrhythmiacondition); to inform that a data transmission has been requested by theremote processing unit; to display a SMS/MMS message received from theremote processing unit; to write a SMS/MMS message to be sent to theremote processing unit, to display the battery charge status; to displaythe status (active/inactive) of signal transmission by the transceiversection 7; to display the status (active/inactive) of electricbiological signal acquisition; and similar.

The processing modules 4 are adapted to control the collection of theanalog electric biological signals, to process the electric biologicalsignals collected by the electrodes, to suitably memorize the processeddata, to run suitable diagnostic algorithms, to operate the transceiversection 7, to operate the user interface 5, to suitably convert theprocessed electric biological signals into files to be transmitted(e.g., according to FTP protocol) to the remote processing unit, andsimilar.

In particular, the processing modules 4 are adapted to carry out ananalog-to-digital (A/D) conversion of the analog electric biologicalsignal collected by the electrodes.

Advantageously, said A/D conversion is carried out according to asampling process having a sampling period T1 and an active sampleacquisition time slot Ts1. In particular, the sampling process isperiodically active for a time slot Ts1 and inactive for a time slotT1-Ts1.

In general, an active sample acquisition time slot refers to the timeslot in which at least one sample is taken and memorized.

The sampling rate 1/T1 is preferably higher than twice the electricbiological signal bandwidth.

For example, in case of ECG acquisition, considering that the bandwidthof the cardiac signal is about 100 Hz, the sampling rate 1/T1 ispreferably higher than 200 Hz.

FIG. 2 exemplarily shows a time diagram of a continuous sampling processwith T1=2 ms (sampling rate of 500 Hz), Ts1=18 μs, and duty cycle(Ts1/T1) of 0.9%.

In the example of FIG. 2, a sample of each of three input channels(corresponding to three electrodes positioned on the patient at theposition of three standard ECG leads) on the input modules 3 is acquired(taken and memorized), 6 μs each, within each time slot Ts1 of 18 μs.

After A/D conversion, the processing modules 4 are advantageouslyadapted to run suitable diagnostic algorithms to identify any anomalouscondition and, if necessary, to command the transceiver section 7 tosend suitable information (e.g., via SMS or file transfer) to the remoteprocessing unit. For example, a SMS informing about the detectedanomalous condition or a file containing the relevant ECG pattern may besent to the remote processing unit.

FIG. 3 exemplarily shows a time diagram of a TDMA transmission processaccording to GSM standard, having a frame rate of 217 Hz, a transmissionperiod (the inverse of the frame rate) T2 of about 4.615 ms, an activetransmission time slot Ts2 of about 577 μs, and a duty cycle (Ts2/T2) of12.5%.

In its turn, FIG. 4 exemplarily shows a time diagram of a TDMAtransmission process according to GPRS and EGPRS standards, having aframe rate of 217 Hz, a transmission period (the inverse of the framerate) T2 of about 4.615 ms, an active transmission time slot Ts2 ofabout 2*577 μs (twice the active transmission time slot of the GSMstandard), and a duty cycle (Ts2/T2) of 25%.

In general, an active transmission time slot refers to the total timeslot in which the transmission takes place and may comprise one or moretransmission sub-units, e.g., of 577 μs each.

As well as for sending suitable information (via SMS or file transfer)to the remote processing unit, the mobile data terminal 8 may establisha radio TDMA communication to exchange service communications with theradio communication network. For example, service communications can beexchanged between the GSM/GPRS/EGPRS mobile data terminal 8 and theradio communication network, according to signaling procedures wellknown in the art, to enable the mobile data terminal 8 to beauthenticated within the radio communication network, its position to beidentified, and similar.

Any time a radio transmission from the transceiver section 7 of themedical device 1 is active, interference with the electric biologicalsignal collected by the electrodes may occur. In particular,interference may occur during each active transmission time slot Ts2.

The present description refers in particular to the interference causedby the transmission of signals from the transceiver section 7 over theradio communication network. As to radio receptions by the transceiver7, it is noted that the radio signals received by the transceiversection 7 from a GSM/GPRS/EGPRS base transmission station (BTS) aretypically very low in power. Therefore, interference between theelectric biological signal collected by the electrodes and any radiosignals received by the transceiver section 7 typically does not lead tointerference problems with the collected electric biological signal. Anyway, if necessary, the principles of the present invention may also beapplied to reduce the effects of the interference between the electricbiological signal collected by the electrodes and any radio signalsreceived by the transceiver section 7.

Typically, the medical device 1 does not support audio/video call, i.e.,there is no exchange of speech or image signals over the radio link. Inthis way, the periods of possible interference between GSM/GPRS/EGPRStransmission and electric biological signal acquisition are limited tothe above mentioned type of communications (SMS, file transfer andsignaling).

Anyhow, GSM signals can be exchanged between the mobile data terminal 8and the radio communication network during a call establishmentprocedure or ringing phase, regardless of the outcome of the procedurethat in a mobile data terminal not supporting audio/video call would endwith a rejection of a call.

The Applicant observed that signal transmission over the radiocommunication network is performed to comply with GSM/GPRS/EGPRSstandards and can be operated any time, by request of the remoteprocessing unit, such as an application server, the patient, thediagnosis algorithm or the radio communication network for servicecommunications. Therefore, signal transmission over the radiocommunication network is out of the control of the processing modules 4,which perform sample acquisition of the analog electric biologicalsignal.

Accordingly, in order to reduce the effects of the interference, theApplicant perceived the need of enabling the processing modules 4 tokeep monitoring the status (active/inactive) of the radio transmissionoperated by the mobile data terminal 8 during the sampling process sothat, when the radio transmission becomes active, the processing modules4 are enabled to prevent acquisition of an electric biological signalsample, which according to the sampling process should start during theactive status of the transmission, from being performed as long as thestatus of radio transmission remains active.

In order to allow monitoring of the radio transmission status, themobile data terminal 8 advantageously provides a logic digital line(herein after called TXSTATE line) for signaling in real time the statusof the radio transmission. For example, said logic line may take a logicvalue ‘0’ to indicate that the radio transmission is inactive and alogic value ‘1’ to indicate that the radio transmission is active.

The logic value of the TXSTATE line will be available at a pin of themobile data terminal 8 that will be electrically connected to acorresponding input pin of the processing modules 4.

By monitoring the logic value taken by the TXSTATE line at said inputpin, the processing modules 4 are thus given the possibility of realtime identifying the radio transmission status.

Monitoring the status of the TXSTATE line is typically performedaccording to microprocessor interrupts procedures well known in the art.

The flowchart shown in FIGS. 5 and 6 outlines the main actions carriedout by the processing modules 4, according to a first preferredembodiment of the invention, to process the electric biological signalcollected by the electrodes in order to reduce the effects of theinterference.

In FIG. 5, at block 100 the processing modules 4 start the process, atblock 101 they perform a initialization process (e.g., by clearing aprocessing modules memory) and at block 102 they set a timer for aninterval of time T1.

At block 103 the processing modules 4 stay in a waiting state, waitingfor one of two possible events: end of the interval of time for whichthe timer is set or change of TXSTATE line from the logic value ‘0’ to‘1’.

When the interval of time for which the timer is set ends, the timer isset again for an interval of time T1 (block 104) and a sample of each ofthe n input channels of the input modules 3 is acquired (blocks 105 to109).

In particular, at block 105 a sample of one of the n input channels istaken.

At block 106 the logic value taken by the TXSTATE line is checked. Ifthe logic value of the TXSTATE line is ‘0’ (that is the radiotransmission in momentarily inactive), the sample is memorized in theprocessing module memory (block 108). Then, at block 109, the processingmodules 4 check if a sample of all n input channels has been acquired.In the affirmative, the processing modules 4 return in the waiting stateof block 103. In the negative, the processing modules 4 loop back toblock 105 to take a sample of another of the n input channels.

If, at block 106, the logic value taken by the TXSTATE line is ‘1’ (thatis the radio transmission in momentarily active), processing modules 4carry out a correction procedure (block 107), before executing thememorizing action of block 108.

For example, according to an embodiment of the correction procedure, theprocessing modules 4 can replace the value of the last taken sample withthe value of the corresponding second-last acquired sample (that is,with the value of the sample memorized in the previous acquisition timeslot Ts1 for the same channel). According to another embodiment, theycan replace the value of the last acquired sample with a null value.

It is noted that the latter embodiment simulates a situation of absenceof electric biological signal that can be suitably handled by thediagnostic algorithm.

When, at block 103, the TXSTATE line value changes from the logic value‘0’ to ‘1’, processing modules 4 set a variable REQUEST to zero (seeblock 110 of FIG. 6) and remain in a waiting state (block 111 of FIG.6), waiting for one of two possible events: end of interval of time forwhich the timer is set or change of the TXSTATE line from the logicvalue ‘1’ to ‘0’.

When the interval of time for which the timer is set ends, theprocessing modules 4 set the variable REQUEST to ‘1’ (block 112) andreturn in the waiting state of block 111.

When the value of the TXSTATE line changes from the logic value ‘1’ to‘0’ (that is, the radio transmission returns to be inactive), theprocessing modules check the value of the variable REQUEST (block 113).If the value of the variable REQUEST is ‘0’ (that is, in the meantimethe interval of time for which the timer was set did not elapsed yet),processing modules 4 return in the waiting state of block 103 of FIG. 5,wherein they wait for one of the two possible events: end of interval oftime for which the timer is currently set (T1) or change of TXSTATE linefrom the logic value ‘0’ to ‘1’.

If at the check of block 113 the value of the variable REQUEST is ‘1’(that is, in the meantime the interval of time for which the timer wasset has elapsed), processing modules 4 set the timer for an interval oftime Tx lower than T1 (block 114) before returning in the waiting stateof block 103 of FIG. 5, wherein they wait for one of the two possibleevents: end of interval of time for which the timer is currently set(Tx) or change of TXSTATE line from the logic value ‘0’ to ‘1’. Thisallows the sampling process performed at blocks 104 to 109 to be resumedwith a delay Tx with respect to the end of the radio transmission(indicated by the passage of the TXSTATE line from the logic value ‘1’to ‘0’ at block 113). For example, Tx meets the following condition:0<Tx≦Ts1.

It is noted that in the flowchart of FIGS. 5 and 6 a not-ending samplingprocess is disclosed. However, the invention also contemplates the casewherein the sampling process is carried out for a predetermined periodof time T3 (e.g., for few hours).

Moreover, it is noted that in the flowchart of FIG. 5, actions at blocks103 to 109 allow the electric biological signal at n input channels ofthe input modules 3 to be periodically sampled with a sampling periodT1. Actions at blocks 104 to 109 are started if the radio transmissionis momentarily inactive (that is if the event “passage of the TXSTATEline from the logic value ‘0’ to ‘1’” at block 103 has not occurredyet). During execution of the actions at blocks 104 to 109, a passage ofthe TXSTATE line from the logic value ‘0’ to ‘1’” does not triggeritself any action. However, after taking each sample, the processingmodules 4 check the status of the radio transmission (block 106 of FIG.5). If in the meantime the radio transmission has become active (thatis, if the TXSTATE line has passed from the logic value ‘0’ to ‘1’”),the sample that has been just taken is corrected according to thecorrection procedure.

Actions at blocks 110 to 114 of FIG. 6 are carried out when the radiotransmission becomes active (i.e., the TXSTATE line passes from thelogic value ‘0’ to ‘1’) during an interval of time (T1-Ts1) in which thesampling process is inactive. According to these actions, a sampleacquisition (including both the action of taking and memorizing thesample), which should start (according to the periodic sampling process)during an interval of time (Ts2) wherein the status of the transmissionis active, is prevented from being performed till the radio transmissionremains active.

Therefore, according to this first embodiment of the invention, thestatus of the radio transmission is monitored. When the radiotransmission becomes active and the sampling process is momentarilyinactive, the sampling process is prevented from becoming active as longas the radio transmission is active. This avoids samples to be acquiredwhen there is a possibility of interference between the electricbiological signal collected by the electrodes and the radio signalstransmitted by the transceiver section 7.

Accordingly, this embodiment of the invention allows the chance ofhaving an active radio transmission time slot (Ts2) to coincide with anactive sample-acquisition time slot (Ts1) to be highly reduced.

Moreover, when the radio transmission becomes active during an intervalof time (Ts1) in which the sampling process is momentarily active, thesample(s) taken during the interval of time (Ts2) in which the radiotransmission is active (and, thus, when interference between theelectric biological signal collected by the electrodes and the signalsradio transmitted by the transceiver section 7 may have occurred) is(are) corrected before memorization.

Considering that the radio transmission is a TDMA transmission that,when operative, is periodically active only for a limited transmissiontime slot (Ts2), at most acquisition of a sample is postponed for aninterval of time Ts2. By over-sampling the electric biological signal(that is by using a sampling rate higher than twice the electricbiological signal bandwidth as, for example, a sampling rate of 300, 400or 500 Hz in case of cardiac signal), any degradation of the acquiredelectric biological signal due to postponement of sample acquisition canbe kept acceptable.

Moreover, any degradation of the acquired electric biological signal dueto postponement of sample acquisition or to sample correction isnegligible with respect to the degradation that would be achieved incase of interference between the electric biological signal collected bythe electrodes and the signals radio transmitted by the transceiversection 7.

FIG. 7 shows a variant of the invention which is similar to thatdisclosed with reference to FIGS. 5 (and 6) apart from the fact that thecheck about the logic value taken by the TXSTATE line (block 106) isperformed after action at block 104 and before action at block 105.

If, at block 106, the logic value of the TXSTATE line is ‘0’ (that isthe radio transmission in momentarily inactive), a sample of one of then input channels is taken at block 105 and memorized in the processingmodule memory at block 108.

If, at block 106, the logic value taken by the TXSTATE line is ‘1’ (thatis the radio transmission in momentarily active), the sample is nottaken and processing modules 4 set the value of the not taken sample tothe value of the corresponding second-last acquired sample or, accordingto a variant, to a null value (block 107′) and memorize such value inthe processing module memory (block 108).

FIG. 8 shows a second embodiment of the invention which is similar tothat disclosed with reference to FIG. 5 apart from the fact that atblock 103 the processing modules 4 stay in a waiting state, waiting foronly one event: end of the interval of time for which the timer is set,and actions of the flowchart of FIG. 6 are not performed.

FIG. 9 shows a third embodiment of the invention which is similar tothat disclosed with reference to FIG. 7 apart from the fact that atblock 103 the processing modules 4 stay in a waiting state, waiting foronly one event: end of the interval of time for which the timer is set,and actions of the flowchart of FIG. 6 are not performed.

Accordingly, in the embodiment of FIG. 8, sample acquisition isprevented by not memorizing the value of the sample(s) taken when theradio time-division-multiplexing transmission is in an active status,correcting the value of such sample(s) and memorizing the value of thecorrected sample(s).

In the third embodiment instead, sample acquisition is prevented bypreventing the samples, which according to the sampling process shouldbe acquired during an active status of the radiotime-division-multiplexing transmission, from being taken and memorizedtill the radio time-division-multiplexing transmission remains in theactive status, and by memorizing a predetermined value for the notacquired samples.

With respect to the second and third embodiment of FIGS. 8 and 9, thefirst embodiment of FIGS. 5, 6 and 7 is preferred in that—besidescorrecting the samples taken during the intervals of time the radiotime-division-multiplexing transmission is in the active status ormemorizing a predefined value for the samples not acquired during theintervals of time the radio time-division-multiplexing transmission isin the active status—it highly increase the chance of having the activeradio transmission time slots (Ts2) and the active sample-acquisitiontime slots (Ts1) interleaved.

1-25. (canceled)
 26. A method of processing in a medical device anelectric biological signal collected from a patient, comprising: a)acquiring a plurality of samples from the electric biological signalaccording to a sampling process wherein each sample is taken from theelectric biological signal and memorized; and b) during the samplingprocess of a), monitoring an active/inactive status of a radiotime-division-multiplexing transmission of signals from the medicaldevice over a radio communication network; and, when the status of saidradio time-division-multiplexing transmission becomes active, c)preventing in a) acquisition of any of the plurality of samples, whichaccording to said sampling process should be acquired during said activestatus of the radio time-division-multiplexing transmission, from beingperformed until the radio time-division-multiplexing transmissionremains in said active status.
 27. The method according to claim 26,wherein the sampling process in a) is periodic with a sampling periodT1.
 28. The method according to claim 27, wherein within each period T1,sample acquisition is performed for a predetermined active time slotTs1, with Ts1<T1.
 29. The method according to claim 28, wherein at leastone sample is acquired within each predetermined active time slot Ts1.30. The method according to claim 29, wherein n samples are acquiredwithin each active acquisition time slot Ts1, wherein n is higherthan
 1. 31. The method according to claim 26, wherein c) is performed bypreventing any of the plurality of samples, which according to thesampling process should be acquired during the active status of theradio time-division-multiplexing transmission, from being taken andmemorized until the radio time-division-multiplexing transmissionremains in said active status.
 32. The method according to claim 30,wherein, when the status of said radio time-division-multiplexingtransmission becomes active, further comprising d) checking if thesampling process of a) is within one of the predetermined active timeslots Ts1.
 33. The method according to claim 32, wherein c) is executedin the negative case of d).
 34. The method according to claim 33,wherein within each active acquisition time slot Ts1 of the samplingprocess of a), after taking each of the n samples and before memorizingthe n sample, further comprising e) checking if said radiotime-division-multiplexing transmission is in an active status.
 35. Themethod according to claim 34, wherein, in the positive case of e), thevalue of the taken sample is corrected according to a predeterminedcorrection procedure and the value of the corrected sample is memorized.36. The method according to claim 33, wherein within each activeacquisition time slot Ts1 of the sampling process of a), before takingeach of the n samples, further comprising e′) checking if said radiotime-division-multiplexing transmission is in an active status.
 37. Themethod according to claim 35, wherein, in the positive case of e), thesample is not taken and a predetermined value is memorized for the nottaken sample.
 38. Method according to claim 26, wherein b) is performedby monitoring the active/inactive status of said radiotime-division-multiplexing transmission after taking each of theplurality of samples in a).
 39. The method according to claim 38,wherein, when the status of said radio time-division-multiplexingtransmission becomes active, c) is performed by not memorizing a takensample.
 40. The method according to claim 39, wherein the value of thetaken sample is corrected according to a predetermined correctionprocedure.
 41. The method according to claim 40, wherein a value of thecorrected sample is memorized.
 42. The method according to claim 26,wherein b) is performed by monitoring the active/inactive status of saidradio time-division-multiplexing transmission before taking each of theplurality of samples in a).
 43. The method according to claim 42,wherein, when the status of said radio time-division-multiplexingtransmission becomes active, c) is performed by not taking the sample.44. The method according to claim 43, wherein a predetermined value ismemorized for the not taken sample.
 45. The method according to claim26, wherein said radio time-division-multiplexing transmission is a timedivision multiple access transmission.
 46. The method according to claim45, wherein said radio time-division-multiplexing transmission isperformed according to at least one cellular transmission standardselected from global system for mobile communications, GPRS and EGPRS.47. A medical device comprising input modules for collecting an electricbiological signal from a patient, processing modules connected to theinput modules, and a transceiver section comprising a mobile dataterminal connected to the processing modules, the transceiver sectioncapable of being adapted to connect to a radio communication network andto transmit and receive signals by using a time-division-multiplexingtransmission, and the processing modules capable of being adapted: a) toacquire a plurality of samples from the electric biological signalaccording to a sampling process wherein each sample is taken from thecollected electric biological signal and memorized; and b) during thesampling process of a), to monitor an active/inactive status of theradio time-division-multiplexing transmission of signals from thetransceiver section; and, when the status of said radiotime-division-multiplexing transmission becomes active, c) to prevent ina) acquisition of any of the plurality of samples, which according tosaid sampling process should be acquired during said active status ofthe radio time-division-multiplexing transmission, from being performeduntil the radio time-division-multiplexing transmission remains in saidactive status.
 48. The medical device according to claim 47, wherein thetransceiver section is capable of being adapted to transmit and receivesignals according to at least one cellular transmission standardselected from global system for mobile communications, GPRS and EGPRS.49. The medical device according to claim 47, wherein the mobile dataterminal is capable of being adapted to provide the processing moduleswith data indicative of the status of the radiotime-division-multiplexing transmission.
 50. The medical deviceaccording to claim 46, comprising an electrocardiograph.